<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>ECMA</title>
    <script type="text/javascript">
        //变量 -> 声明变量 -> 类型+变量名
        //var: variable
        var a;
        console.log(typeof a);
        a = 1;
        a = 3.14;
        console.log(typeof a);
        a = true;
        console.log(typeof a);
        a = "hehe";
        console.log(typeof a);
        a = new Date();
        console.log(typeof a);
        //==:判断内容，不是类型
        //===:比较类型和内容

        var b;
        b = new Date();
        if (b == 1){
            console.log(true);
        }else {
            console.log(false);
        }

        var c;
        c = 1;
        c = "1";
        if (c === 1){
            console.log(true)
        }else {
            console.log(false);
        }
    </script>
</head>
<body>

</body>
</html>